The Lie Detector
by Dynamaster
Summary: Beckett and Castle meet Captain Montgomery's daughter. After one certain trip to the interrogation room they find out she has an amazing talent. One that could help them out a lot.
1. Chapter 1

The Lie Detector

A single file line of 5th graders were walking through the 12th precinct. All of them chattering and excited. Castle nodded his head at the line of kids "They here on a field trip?" "I guess" Beckett responded shrugging "Montgomery didn't say anything about a field trip today, though". As they both watched the line of kids, they noticed one girl at the back of the line, nagging behind. She was about 5'', african-american, with shoulder length black hair.

She was looking around the precinct when her eyes finally settled on Castle. _That couldn't be Richard Castle_, the girl thought. Her eyebrows furrowed together as if she were confused. _Oh my gosh that is!_, the girl then thought. Her eyes got wide in a mixture of surprise, awe, and admiration as she hurried over. "Do you know her?" Beckett asked with a raised eyebrow and a half smile. "I don't think so" Castle answered as he knitted his eyebrows together. "You-You-You're Richard Castle!" the girl stuttered "Will you autograph my books!" she exclaimed as she pulled out at least three Nicki Heat books.

Castle raised his eyebrows "Ah, sure". The girl pulled out a black sharpie and handed it to him. As he signed the books she took in Beckett, and her eyes widened again. "You're Nicki Heat, I mean Kate Beckett, Detective Kate Beckett! Will you autograph my books too, please?" "Um, yeah-okay" Beckett responded surprised that the girl wanted her autograph. "Wait" Castle interrupted Beckett's thoughts "You read my books?" "Yes" the girl answered, "Why?" "Well, my books are for adults" he responded.

_I totally forgot about that_, the girl thought. "Uhh" the girl said as she grabbed the books and the sharpie back and looked around for an excuse "Let's just say, I read above my grade level. I have to get back to my class" she finished hurriedly. "Bye!" she said as she hurried back to the line. "Castle" Beckett said turning toward him "Did she look sort of familiar to you?" "Kind of" Castle replied nodding. "Where have we seen her before?" Beckett asked while lost in thought. "I don't know" Castle responds his mind flipping through his memories.


	2. Chapter 2

**Dynamaster- I didn't know how to put the author's note in at first because this is my first fanfic. But, I figured out how to now. I am so excited. I am really glad you guys like my story. This story is set before Captain Montgomery's death.**

Three Hours Later

The precinct had already quieted down since the kids had left. The front doors opened and the girl from earlier that day walked in. Castle and Beckett walked over to meet her. "Hi" they both greeted, surprised to see her. "Oh" she widened her eyes "Hi Detective Beckett, Hi Mr. Castle" "Oh, it's just Castle" Castle explained. "Oh, okay" the girl said. "So, what are you doing here?" Beckett asked.

"Oh" the girl gulped "I-I'm waiting for my dad". She let slip a small smile as though she was hiding something. "We never caught your name" Castle realized. "Yeah, that's right, you know ours but we don't know yours" Beckett smiled while brushing a strand of brunette hair out of her face. "My name's Kelly" she announced. "Kelly" Beckett mumbled trying to register where she had seen her before.

"Kelly Montgomery" the girl finished. Kate's green eyes sparkled "You're Captain Montgomery's daughter!" she declared. "Correct" Kelly said with a smile while pointing at Beckett. "That's where we've seen you before, at your father's house when we were there for business" Castle broke in. "I don't remember you guys at my house" Kelly replied with a furrowed brow. "You were never home, but we saw pictures of you and your sister everywhere" Castle recalled.

The door to Capt. Montgomery's office opened and Capt. Montgomery walked out. "Hi, daddy!" Kelly greeted. "Hi, pumpkin!" Capt. Montgomery laughed as he walked over to hug her. "I see you've met Detective Beckett and Richard Castle" "We're on our way to the interrogation room sir to talk to Nicholas Pines" Beckett declared. "Nice, see what you can find out" Capt. Montgomery decreed.

"You going home early sir?" Castle asked. "Yes" Capt. Montgomery answered "Today's my wife's birthday and I'm taking her out to dinner". "Tell her we said Happy Birthday" Beckett grinned. "I will, Goodnight Beckett, Castle" Montgomery responded. "Night, sir" Beckett and Castle both called. "Nice meeting you Kelly" Beckett proclaimed. "Yeah, nice meeting you" Castle echoed. "Nice meeting you guys too" Kelly smiled. Beckett and Castle then walked away to the interrogation room.


	3. Chapter 3

**Disclaimer: I do ****not**** own Castle.**

"Oh, I forgot my coat" Montgomery realized "Let me go get it honey. "Okay" Kelly grinned. _I wonder what the interrogation room is like,_ Kelly thought. Curious, she followed the path Beckett and Castle had walked. Then she walked through a door to a dark room with a large window. _This must be the window that looks like a mirror inside the actual interrogation_ _room_, thought Kelly, _I've heard of these, they're called one-way mirrors. _

Kelly watched as Beckett slammed her hand down on the interrogation table, trying to get a confession out of a suspect. "Wow" breathed Kelly in amazement and admiration of Kate's tactics. "So, you did not go to Clarisse's party that night?" Castle asked. "No" Nicholas replied "I wasn't at the party that night". "Were you at Warehouse 118 that night?" Beckett persisted.

"No, I wasn't there either" Nicholas answered. Kelly's extra sense kicked in, the one that let her know when people are lying. She zoned in on the slight flutter of Nicholas' eyelashes when he answered Beckett's question. "Are you done questioning me?" Nicholas asked. "That's it" Beckett admitted. Then she and Castle walked through the door that was next to the window and into the dark room.

"He was lying" Kelly told them as soon as they walked through the door. "What?" Beckett asked. "He was lying, about not being at the warehouse" Kelly clarified. "What. How do you know?" Capt. Montgomery asked. So swept up in her surroundings, Kelly didn't even notice her father sneak up beside her. "I can tell when people are lying" Kelly explained. "What do you mean?" Castle asked. "Well, everybody has their tells, no matter how small they may be" Kelly disclosed.

"Well, ready to go pumpkin?" Capt. Montgomery asked. "Yeah, dad" Kelly answered. Capt. Montgomery and Kelly left the precinct. Castle and Beckett walked out of the interrogation room and to Beckett's desk. "Ryan, Espo, pull up Warehouse 118 security cameras and see if you spot Nicholas Pines. Castle and I will talk to Clarisse and see what she knows" Beckett commanded.


	4. Chapter 4

**Disclaimer: I do ****not**** own Castle.**

_The Next Day_

_ Is that my dad's car?, _Kelly thought as school let out for the day. "Dad" she called out as she saw her dad in the driver seat of his deputy car "I thought I was walking home today". 'Well, something came up at the precinct and we need you there" he explained. "Why?" Kelly asked. "We have a few questions for you" Capt. Montgomery answered as Kelly got in the car. "Ooo, being questioned by police, should I be scared?" Kelly asked playfully.

"Yes, very" Capt. Montgomery smiled. During the car ride, Kelly told her dad about her day at school. At the precinct, she followed her dad into his office and found Detective Beckett, Castle and two cops she had never met before. Kelly's heart started beating a little bit faster than normal. "Kelly, this is Detective Ryan and Detective Esposito" Beckett said gesturing to each detective in turn. Kelly nodded and waved to each and they nodded and waved back. "Look, just tell me now, am I in trouble?" Kelly nervously asked.

"Oh, no" Castle began "quite the opposite". "You see, yesterday Detectives Ryan and Esposito checked the Warehouse 118 security cameras and…" Beckett gestured to them. Ryan continued for her "We saw Nicholas Pines at the Warehouse". "Yesterday, you told them" he gestured to Castle and Beckett "that he was lying, and you were right" Esposito said. "Now, it could have been a lucky guess" Beckett started. "But, we don't think so" Castle finished. "So, we just want to know how you can tell when people are lying" Beckett explained.

Kelly exhaled slowly "Okay, it all started in Kindergarten. When the kids were lying, I zoned in on the slight tremble of their hand, the slight waver of their foot. That's when I noticed I had this… well, I wouldn't really call it a gift, more like a talent. Nowadays in school, my friends all come to me when they want to know if someone is lying. My nickname at school is "The Lie Detector". To know if someone is lying, I have to be looking at them and I have to be paying attention to them." Kelly explained. "How come your mom and I don't know?" Capt. Montgomery asked. "I dunno" Kelly shrugged.

"Does anybody in the family know?" Capt. Montgomery asked. "Chloe does" Kelly answered. "Is Chloe your sister?" Castle asked. "Yeah" Kelly nodded. "Older or younger?" Castle asked. "She's older by two years" Kelly answered "she's thirteen". "Why does your sister know and your mom and I don't?" Capt. Montgomery asked. "She's lied to me a few times and I've caught her in her lies" Kelly answered. "We were wondering if you would want to help us out, here at the precinct?" Beckett asked with a smile.


	5. Chapter 5

**Disclaimer: I do ****not**** own Castle.**

**This chapter is dedicated to all of the people I love out there, including Bubble, Nana, and Destiny.**

"Really!" Kelly exclaimed with wide eyes and a big smile plastered across her face. "Yeah, we could really use your help in the interrogation room" Castle added. "Think you'll have enough time?" Capt. Montgomery asked with a smile. "Well, considering it's my last week of school, I think I'll have more than enough time" Kelly said with a giggle. "Oh, I forgot about that" Capt. Montgomery chuckled. "Wait a sec, speaking of my sister, a minute ago. Where is she?" Kelly asked. "You didn't notice your sister wasn't with us?" Capt. Montgomery asked back. "I don't spend every waking moment of my life thinking about her" Kelly replied. "Well, your mother picked her up from school and took her to her dentist appointment" Captain Montgomery explained. "When do you want me to start?" Kelly asked with a smile. "Can you start tomorrow?" Beckett asked. "Sure" Kelly answered. "Great, be here tomorrow after school" Beckett declared. "Okay, I will" Kelly confirmed.

_The Next Day_

"We found a body this morning at the Smarkez Hotel" Castle began. "The vic's name is Marcus Binds" Beckett finished. "He works as a doorman at the hotel" Esposito explained. "So far, our number one suspect is Lorraine Dulce. She lives at the hotel" Ryan explained. "She's in the interrogation room right now" Beckett said. Beckett and Castle walked into the interrogation room. Kelly walked into the observation room. Beckett and Castle sat at the table with the suspect and Kelly looked through the one-way mirror at the suspect. "Ms. Dulce, I'm Detective Beckett. This is my partner, Richard Castle" she gestured to Castle. "We'd like to ask you a few questions". Lorraine looked around nervously "O-Okay" she stuttered. "Ms. Dulce, where were you last night between 9 pm and 11 pm?" Beckett asked. "I was at my friend's house" Lorraine answered. Kelly zoned in on her face and saw the corner of her lips twitch. "Did you see anything suspicious before you left?" Castle asked. "There was this shady guy that checked in. He was Caucasian but had really tan, dark skin. He had black, shaggy hair and piercing dark eyes that seemed like they were looking right through you, or into your soul" she admitted.

"Well, thank you for your time and information Ms. Dulce" Beckett concluded. "We'll keep you updated on the case" Castle said. They got up and walked into the observation room. "She was lying about being at her friend's house" Kelly reported. They all walked out of the observation room. "I wonder why?" Beckett asked as she sat down at her desk. "Maybe she's part of a conspiracy" Castle suggested. "A conspiracy?" Beckett asked with a raised eyebrow. "I saw this once in a movie" Castle recalled "the lady said she was at her friend's house at the time of the murder to cover up the conspiracy". "It's a movie, Castle" Beckett reminded him. "But, conspiracies are real" Castle replied. Beckett rolled her eyes. Kelly smiled at their easy-going banter. "Ryan, Espo, Check the security cameras and list of guests and find out who our mystery person is" Beckett commanded "We will talk to the manager and see what he knows".


	6. Chapter 6

**Author's Note: School starts next week so my updates will become less and less frequent. But, I would like to thank everyone out there who is reading my story and thank you for all of the positive feedback. **

**Disclaimer: I do ****not**** own Castle.**

_The End of the Day_

"Hey, Beckett" Castle said smiling "want to go to the movies? I heard that, that new movie, Mother Zombie, is out". Beckett took a breath and hesitated for a second, then said "Sure, Castle" She grabbed her jacket off the back of her chair. "Bye" they called to Kelly. Kelly smiled and gave them a small finger wave, "Bye". Castle and Beckett both walked out of the precinct together, in long, smiling conversation. When her dad came out of his office, Kelly asked him a question that had been itching her all day. "Dad" she asked, "Are Beckett and Castle-" "Dating" Capt. Montgomery finished, "No, they aren't. But, there is something between them. We can all see it".

_A few days later- First day of Summer Vacation_

"Yes!" Kelly exclaimed as she burst through the precinct doors, backpack slung over one shoulder. "First day of Summer Vacation!" she exclaimed as she walked over to Beckett's desk and sat down. "I am free!" she pronounced with her arms in the air. "Until next year" Castle added. "I'm trying not to think about that" Kelly responded. "Smart Girl" Castle persisted. "Do you want to come with us and see the bodies in the mornings, now?" Beckett asked "so you can look around the crime scene for anything that might be helpful". "Umm-" Kelly grimaced "No thanks". Beckett looked up from her paperwork. "What's wrong?" she asked. "I-I just have a problem with dead bodies, that's all" Kelly mumbled. "That's okay, you could just meet us at the precinct after we check out the body" Beckett explained. "Cool, what time?" Kelly asked. "Could you be here around 9:00 am?" Beckett wondered. "Sure" Kelly responded.

_Next Morning_

Castle handed Beckett a cup of coffee. "Thanks" Beckett smiled taking the coffee cup from his hand and sipping it. "Our vic's name is Janelle Daniels, she's your school district's superintendent" Beckett said addressing Kelly. "Wow" Kelly breathed "She was murdered?" Castle nodded "We found her at Trilatory School". "The only people that were there, were two teachers and ten students" Beckett continued. "They were there for some summer program" Castle finished. A cop walked over to Beckett's desk with a file in his hand. "This is a list of people who were at Trilatory at the time of the murder" he said. He opened the file "The two teachers, Mrs. Marissa Piercen and Mr. Larsen Gonzalez. The ten kids, Jessica Caldwell, Rebecca Dean, Jacob Anderson, Danielle Andrews, Benjamin Stockholm, Monica Belldwin, Marcus Tetherman, Stanley and Maria Jenson, those two are related, they are twins, and a Chloe Montgomery" he finished.


	7. Chapter 7

** Disclaimer: I do ****not**** own Castle.**

Kelly threw the pencil she was holding up in the air. "My sister!" she exclaimed with wide eyes. "Is Chloe Montgomery in the interrogation room right now?" Kelly asked hurriedly. "Yes" the cop answered. Kelly flew out of her chair and ran to the observation room She saw a detective asking Chloe questions. Castle and Beckett had come in behind her. She turned towards them "Can I talk to my sister, please?" she asked hurriedly. "We can't-" Beckett started.

"Please, really quickly?" Kelly interrupted. Beckett looked into Kelly's pleading eyes, hesitated, then pressed the button next to the microphone and spoke into it "Tell Detective James to come out of the interrogation room now". Kelly walked into the interrogation room as the detective walked out. "Kelly!" Chloe cried out in a mixture of surprise and desperation. "Chloe!" Kelly cried out, eager to talk to her sister.

"What's going on?" Kelly asked sitting down. "I don't know, you tell me!" Chloe responded. "You know that Ms. Daniels was murdered this morning, right?" Kelly asked. "Yes" Chloe answered. "And, you know that she was murdered at Trilatory where you were for the summer program, right?" Kelly asked. "Yes" Chloe repeated. "Ok, where were you at the time of the murder?" Kelly asked. "I was in the hallway… with her body" Chloe admitted.


End file.
